Processing of waste and especially hazardous waste, is a continuing problem for many industries and in non-industrial settings. Landfill space is decreasing and costs are rising. Moreover, the shipment and processing of hazardous waste can pose a significant risk to public health and the environment. In view of these concerns, the public and industry have long sought waste processing solutions that reduce waste volume, detoxify hazardous content and/or neutralize or stabilize waste products to prevent undesired spreading through leaching, airborne discharge or the like.
A particularly challenging problem is the treatment and disposal of heterogeneous waste, i.e., waste materials that are highly variable in their chemical composition and physical properties. Such waste may include organics, inorganics and mineral compounds and may be in the form of solids, liquids or mixed phase materials. Heterogeneous waste is produced in many environments including households, semiconductor fabrication facilities, chemical and petrochemical industrial plants, hospitals, military bases, chemical and nuclear weapon production facilities, and fossil fuel and nuclear power plants.
Conventional waste processing reactor systems generally lack the versatility needed to effectively handle a broad range of heterogeneous waste. Such systems typically process waste in a reactor chamber that is heated by a plasma torch, or an induction or joule effect heater. Unfortunately, each of these reactor types has disadvantages for processing certain types of waste. For example, induction heaters are problematic for certain types of waste. In particular, induction heaters are suitable mostly for melting metal and their efficiency and effectiveness are greatly reduced when the waste contains other materials such as cellulose and plastic. Plasma heaters, on the other hand, do not have space requirements suited for complete reaction and polishing of effluent gases over the reactor bed in many applications. Single zone joule effect reactors are, however, problematic for processing waste streams that may contain metallic materials. Joule effect heaters employ a pair of electrodes that extend into the reactor bed to electrically heat the reactor bed as well as the waste contained in the reactor bed. Any molten metallic materials in the waste can provide a conductance path between the electrodes and short-circuit the electrical resistance that generates the joule effect heat.
Thus, most feed preparation operations require sorting and contact handling by the operators to reduce the size of objects and remove objects that are not suitable for processing by the particular heater type or configuration of the reactor system. For example, where joule effect heating is employed, the feed waste materials must be sorted to remove metallic elements, a rather time consuming and costly process. Handling of waste objects, especially in the case of biomedical, infectious, or radioactive waste, can also jeopardize the health and safety of the operator.
Another disadvantage of current reactor systems are their inability to prevent various waste batches from mixing (or co-mingling) with one another. In a typical operation, the inert components of the various waste feed batches mix with one another, accumulate in the bottom of the chamber and melt as a single homogeneous glass matrix.
Accordingly, an improved waste reactor system is, therefore, desirable.